West Control Solutions KS 800 CANopen Interface Manual - Manual (Page 13)

KS 800 CAN-Interface
3.3.2 Synchronous send PDO
The master sends SYNC pulses for actual process value refreshment. The number of Sync mes-
sages after which must react can be configured by the master. The default setting is "1". (see
Transfer-Type, chapter 3 Process-Data-Objekts)
During synchronous operation, a channel starting with the first one is sent after each Sync mes-
sage (if transfer-type = 1 ). Subsequently, all further channels are sent successively. After the
last channel, a new cycle is started at the first one. If the two send PDOs are configured as
synchronous PDOs, two channels are transmitted simultaneously. The following diagram explains
the interactions of Sync message and PDOs.
3.3.3 Asynchronous receive PDO
When an asynchronous PDO is received, the contained data are passed on to the controller
module with the next kommunucation -modul-cyclus. The data are written into the buffer accor-
ding to channel number. Thereby, the fReceived flag is set. This signals that new data for the
controller are ready for receiving. The fReceived flag is reset by the controller.
Caution: When passing new data to the controller, the communication module does not check,
if the controller has already taken over the data received last.
(Scanning rate must be taken into account.) i.e. PDOs can be overwritten, earlier
information will be lost.
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